INSECT FOOD OF GRAY GROSBEAK. 



31 



and In certain years has caused a decrease in the crop of a quarter of 

 a million bales, valued at $25,000,000. Many birds devour great 

 numbers of cotton worms, and this fact alone justifies the oft-repeated 

 statement that " too much can hardly be said in favor of insectivorous 

 birds in cotton fields." The gray grosbeak assumes a proper share in 

 this valuable work, 14 of the 71 individuals examined having con- 

 sumed cotton worms, which formed an average of 39.1 percent of 

 their food. As many as 18 caterpillars were found in a single 

 stomach. Another caterpillar enemy of 

 the same ,crop, the cotton cutworm (Pro- 

 denia ornithogalli, fig. 9), also is freely 

 devoured. 



As beetles were less esteemed than cater- 

 pillars by the gray grosbeak, so also are 

 the latter less liked than the Orthoptera. 

 This group contributes 11.52 percent of the 

 total food. Both long and short-horned 

 locusts and their eggs are devoured, 7 or 8 

 grasshoppers sometimes being secured by a 

 single bird. The only species (Syrbula 

 admirabilis) identified sometimes feeds on 

 timothy. 



True bugs, comprising stink-bugs (Pen- 

 tatomidae) and their eggs, cicadas, leaf- 

 hoppers (Jassida?), and lantern flies (Ful- 

 goridse) compose about 1.5 percent of the 

 food. All of these insects are injurious 

 and the bird does a service by feeding 

 upon them. 



One parrot-bill was bold enough to 

 swallow a large hornet (Vespa sp.). A 

 few ants also were eaten, and these, together with spiders and snails, 

 complete the list of animals devoured. Although this grosbeak is not 

 conspicuously insectivorous, almost all the insects it eats are injurious. 



Mineral Matter. 



While mineral matter was absent from the majority of the stomachs 

 examined, enough was contained in the remainder to make an aver- 

 age of 3.62 percent for the whole number. 



Summary. 



The present -incomplete data indicate that for a grosbeak the par- 

 rot bill is decidedly vegetarian, preferring vegetable food even in 

 months when insects abound. More than 69 percent of its food 

 during August and September consists of weed seeds, the small 



18848— Bull. 32—08 3 



a 



Pig. 20. — Cotton ' worm (Ala- 

 bama argillacea). (From 

 Riley, Bureau 

 ogy.) 



of Entomol- 



